Secondary Hardening of T24 Steel Weld Joints Performed at Incorrect Interpass Temperature and Low Temperature Heat Treatment

Kód výsledku v IS VaVaI

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Výsledek na webu

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DOI - Digital Object Identifier

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Jazyk výsledku

angličtina

Název v původním jazyce

Secondary Hardening of T24 Steel Weld Joints Performed at Incorrect Interpass Temperature and Low Temperature Heat Treatment

Popis výsledku v původním jazyce

The efficiency of power plants is depending on the steam temperature and/or the steam pressure. Efficiency increasing from 35% to 42-45% require increasing of the steam temperature over 600oC and the pressure over 26 MPa. According to the designer opinion it is not profitable to use classical low alloy creep resistant steels 16Mo3, 13CrMo4-5 or 10CrMo9-10 for membrane waterwall construction for these service condition. New modified low alloy creep resistance T23 and T24 (7CrMoVTiB10-10) steels were developed for membrane waterwalls. Welding of these steels with small thickness (around 6.3 mm) should be enabled without preheating and post weld heat treatment (PWHT) due to the lower carbon content below 0.1%. High creep rupture strength (CRS) values are achieved by Ti, N and B elements alloyed to T24 steel. The original expectation that the welding small thickness without preheating was early overcome and was wrong. According to the present experience the T24 steel is welded with preheating at 150-250oC depending on the wall thickness and welded joint toughness in order to achieve required hardness and impact toughness values.

Název v anglickém jazyce

Secondary Hardening of T24 Steel Weld Joints Performed at Incorrect Interpass Temperature and Low Temperature Heat Treatment

Popis výsledku anglicky

The efficiency of power plants is depending on the steam temperature and/or the steam pressure. Efficiency increasing from 35% to 42-45% require increasing of the steam temperature over 600oC and the pressure over 26 MPa. According to the designer opinion it is not profitable to use classical low alloy creep resistant steels 16Mo3, 13CrMo4-5 or 10CrMo9-10 for membrane waterwall construction for these service condition. New modified low alloy creep resistance T23 and T24 (7CrMoVTiB10-10) steels were developed for membrane waterwalls. Welding of these steels with small thickness (around 6.3 mm) should be enabled without preheating and post weld heat treatment (PWHT) due to the lower carbon content below 0.1%. High creep rupture strength (CRS) values are achieved by Ti, N and B elements alloyed to T24 steel. The original expectation that the welding small thickness without preheating was early overcome and was wrong. According to the present experience the T24 steel is welded with preheating at 150-250oC depending on the wall thickness and welded joint toughness in order to achieve required hardness and impact toughness values.

Druh

D - Stať ve sborníku

CEP obor

JP - Průmyslové procesy a zpracování

OECD FORD obor

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Projekt

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Návaznosti

S - Specificky vyzkum na vysokych skolach

Rok uplatnění

2016

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název statě ve sborníku

Advances in materials technology for fossil power plants : proceedings from the 8th international conference : October 11-14, 2016, Albufeira, Portugal

ISBN

978-1-62708-131-3

ISSN

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e-ISSN

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Počet stran výsledku

9

Strana od-do

1002-1010

Název nakladatele

ASM International

Místo vydání

Materials Park

Místo konání akce

Albufeira

Datum konání akce

11. 10. 2016

Typ akce podle státní příslušnosti

WRD - Celosvětová akce

Kód UT WoS článku

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